Death In The Clouds by Agatha Christie

From seat No.9, Hercule Poirot was ideally placed to observe his fellow air passengers. Over to his right sat a pretty young woman, clearly infatuated with the man opposite; ahead, in seat No.13, sat a Countess with a poorly-concealed cocaine habit; across the gangway in seat No.8, a detective writer was being troubled by an aggressive wasp. What Poirot did not yet realize was that behind him, in seat No.2, sat the slumped, lifeless body of a woman.

There are more important things than finding the murderer. And justice is a fine word, but it is sometimes difficult to say exactly what one means by it. In my opinion the important thing is to clear the innocent.
Hercule Poirot, Death in the Clouds

More about this story

This story is a classic locked room mystery, a technique at which Agatha Christie excelled. One of the twelve people aboard a flight from London to Paris must have murdered Mme Giselle, who past appears to be filled with those who might seek revenge.

In 1935, the year this novel was published, a regular London-Paris air service began – using converted bombers for the aircraft. Agatha Christie was a huge fan of air travel, having taken her first flight in 1911, she described the experience as extraordinary.

The book was first published in the US and titled Death in the Air. It was adapted for TV in 1992, starring David Suchet and included the added character of Inspector Japp. In 2004 there was a Japanese manga edition of the story which was adapted for TV as anime later that year. It appeared in four parts and was only broadcast in Japan. Poirot is accompanied by Miss Marple's great niece.